Effects of Methylmercury Contained in a Diet Mimicking the Wayana Amerindians Contamination through Fish Consumption: Mercury Accumulation, Metallothionein Induction, Gene Expression Variations, and Role of the Chemokine CCL2.
Methylmercury (MeHg) is a potent neurotoxin, and human beings are mainly exposed to this pollutant through fish consumption. We addressed the question of whether a diet mimicking the fish consumption of Wayanas Amerindians from French Guiana could result in observable adverse effects in mice. Wayanas adult men are subjected to a mean mercurial dose of 7 g Hg/week/kg of body weight. We decided to supplement a vegetarian-based mice diet with 0.1% of lyophilized Hoplias aimara fish, which Wayanas are fond of and equivalent to the same dose as that afflicting the Wayanas Amerindians. Total mercury contents were 1.4 ± 0.2 and 5.4 ± 0.5 ng Hg/g of food pellets for the control and aimara diets, respectively. After 14 months of exposure, the body parts and tissues displaying the highest mercury concentration on a dry weight (dw) basis were hair (733 ng/g) and kidney (511 ng/g), followed by the liver (77 ng/g). Surprisingly, despite the fact that MeHg is a neurotoxic compound, the brain accumulated low levels of mercury (35 ng/g in the cortex). The metallothionein (MT) protein concentration only increased in those tissues (kidney, muscles) in which MeHg demethylation had occurred. This can be taken as a molecular sign of divalent mercurial contamination since only Hg(2+) has been reported yet to induce MT accumulation in contaminated tissues. The suppression of the synthesis of the chemokine CCL2 in the corresponding knockout (KO) mice resulted in important changes in gene expression patterns in the liver and brain. After three months of exposure to an aimara-containing diet, eight of 10 genes selected (Sdhb, Cytb, Cox1, Sod1, Sod2, Mt2, Mdr1a and Bax) were repressed in wild-type mice liver whereas none presented a differential expression in KO Ccl2(-/-) mice. In the wild-type mice brain, six of 12 genes selected (Cytb, Cox1, Sod1, Sod2, Mdr1a and Bax) presented a stimulated expression, whereas all remained at the basal level of expression in KO Ccl2(-/-) mice. In the liver of aimara-fed mice, histological alterations were observed for an accumulated mercury concentration as low as 32 ng/g, dw, and metal deposits were observed within the cytoplasm of hepatic cells.
(International Journal of Molecular Sciences. vol. 13, n° 1661-6596, pp. 7710-38, 12/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UPMC, INSERM, CNRS, IBGC, UB, CNRS
Élimination des micropolluants par les stations d'épuration domestiques
Les stations d'épuration domestiques n'ont pas été conçues pour traiter les micropolluants. Elles en éliminent cependant une quantité non négligeable, essentiellement par sorption sur les boues, associée à une dégradation par voie biologique pour certaines substances. Cet article synthétise les principaux acquis récents concernant le comportement des micropolluants dans les filières de traitement des eaux (primaires, secondaires, tertiaires) et dans les filières boues associées. Il présente également les recherches en cours sur l'amélioration des procédés de traitement et leurs perspectives. / Domestic wastewater treatment plants were not designed for micropollutants removal. They perform substantial removal of several micropollutants, mainly by sorption process onto biological sludge and by biodegradation from the liquid phase for some substances. This article presents the main recent advances on the fate of micropollutants through primary, secondary and tertiary treatment processes. It also addresses research in progress for the optimization of micropollutants removal.
(Sciences Eaux & Territoires, n° 2109-3016, pp. p. 6 - p. 15, 12/04/2026)
UR MALY, IRSTEA, CIRSEE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UMR Qualisud, Cirad, UM1, UM2, Montpellier SupAgro, AU, UR, UM, Montpellier SupAgro
Distribution of trace elements in waters and sediments of the Seversky Donets transboundary watershed (Kharkiv region, Eastern Ukraine)
This paper reports on the aquatic chemistry of trace elements in terms of spatial and temporal distribution, but also pollution sources in the transboundary watershed of the Seversky Donets River (Ukraine/Russia). Bed sediments and filtered water were collected from the Udy and Lopan Rivers at sites from the river source in the Belgorod region (Russia) to rural and urban areas in the Kharkiv region (Ukraine) in May and August 2009. Priority trace elements (As, Cd, Cr, Cu, Hg, Ni, Pb and Zn), an urban tracer (Ag) and additional metals (Co, Mo, V) and Th were measured in stream water and sediments. The low levels and variability of Th-normalized concentrations indicated the absence of geochemical anomalies in the upstream part of the rivers and suggested that these data represent a regional baseline for trace elements in bed sediments. In contrast, water and sediments within the city of Kharkiv were contaminated by Ag, Pb, Cd, Cu, Cr and Zn, which are mainly attributed to municipal wastewater inputs and urban run-off. Results of the environmental quality assessment showed that element concentrations in the sediments can be considered as potentially toxic to aquatic organisms in sites downstream of the wastewater discharges.
(Applied Geochemistry. vol. 27, n° 0883-2927, pp. 2077-2087, 12/04/2026)
UB, ENSEGID, Ghymac, UB, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ISTO, BRGM, INSU - CNRS, UO, CNRS
Indice Diatomique Réunion (IDR): a new river diatom index dedicated to a specific ultramarine and tropical biogeographical context
The Water Framework Directive (JOCE 2000) needs to be applied on the European continental area as for other ultramarine territories as French overseas departments (in our case, Reunion Island). For such specific territories with a strong biogeographical concern, biological indexes set-up and validated in continental Europe cannot work properly. The main problems encountered result from strong specificities in the field of geochemical and climatic conditions, of taxa list and of their local ecology. Under the joint demand of the Reunion Water Office, local services of Environment Ministry (DEAL Reunion) and ONEMA, a scientific consortium grouping ASCONIT Consultancy and IRSTEA drove a 3 year-study based on network sites and other particular sites, aiming to: 1) describe in situ abiotic environmental condition of rivers (physico-chemistry, chemistry, descriptors of general ambiance like shading, flow velocity, depth...); 2) identify and count relative abundances of taxa; and 3) set-up a new Diatom Index dedicated to Reunion, based on relationships between abiotic descriptors and taxa ecology. The study was based on 256 samples and records obtained during 3 years at 55 different sites along five field campaigns covering 2 different seasons. A huge work was to identify and count the species in this new context. 343 different species have been observed, of which 162 determined at the species level. 28 other species were close to a known species (cf or aff.), 153 identified at the genus level were given a number code at the species level. 175 enough occurring species were used to build the index and were given an ecological profile. Because of a very dilutive context, we chose to principally base the index calculation on a list of alarm taxa named "Taxa –", which presence is synonym of strong anthropogenic alteration. This new index provides satisfying assessment results which will be presented.
(pp. 1, 12/04/2026)
UR REBX, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Use of Mixed-Mode Ion Exchange Sorbent for the Passive Sampling of Organic Acids by Polar Organic Chemical Integrative Sampler (POCIS)
Acidic herbicides are increasingly monitored in freshwater, since their high solubility favors their rapid transfer to the water phase. Therefore, contaminant levels in the water can vary rapidly and passive sampling would be preferred over spot sampling to integrate all pollution events over a given exposure time. In this work, we propose to compare the conventional pharmaceutical polar organic chemical integrative sampler (POCIS) with modified POCISs containing two different receiving phases: a standard polystyrene divinylbenzene polymer with a higher specific surface area (Chromabond HR-X) and a mixed-mode anion exchange sorbent providing additional strong anion exchange interaction sites (Oasis MAX). Due to its hydrophobic character, Chromabond HR-X had little interaction with water (no sampling of acidic herbicides); whereas Oasis MAX provided acceptable sampling parameters (longer kinetic regime together with higher sampling rates). Additional experiments with POCIS-MAX showed no influence of nitrates on analyte uptakes, and linear isotherms reaching 10 μg L−1, supporting the applicability of this device for the sampling of organic acids in continental water. The performance and reference compound (PRC) approach would be then applicable for POCIS-MAX if no competition is observed with other anions, especially organic acids (e.g., humic acids).
(Environmental Science and Technology. vol. 46, n° 0013-936X, pp. 13344-13353, 12/04/2026)
UR REBX, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Effets du cadmium sur l’expression génétique de l’espèce Eolimna minima
Les systèmes aquatiques sont fortement impactés par les activités anthropiques et par les diverses pollutions qui en découlent. Parmi ces pollutions, les contaminations aux métaux lourds sont particulièrement préoccupantes du fait des effets toxiques avérés qu’elles entraînent. Le développement d’outils adaptés à l’évaluation de la qualité des eaux est dans ce contexte un enjeu fondamental. Les diatomées benthiques d’eau douce sont considérées comme un maillon bio-indicateur intéressant, qui les ont fait retenir comme élément biologique-clé par la DCE et ont conduit à leur utilisation dans divers indices de qualité des eaux comme l’Indice Biologique Diatomées (IBD) appliqué au niveau européen. Cependant, ces indices ont montré leurs limites dans l’évaluation de la qualité des eaux face à des pollutions de type métallique. C’est pourquoi de nouvelles approches sont amenées à voir le jour dans l’évaluation de la qualité des eaux. Dans notre étude, l’impact du Cd au niveau génétique est évalué par PCR-q sur 9 gènes d’intérêt suite à une exposition en conditions contrôlées de laboratoire de l’espèce eolimna minima, la cinétique de croissance de la population et la bio-accumulation sont suivies. La cinétique de population montre un fort impact du Cd à la concentration de 100µg Cd/L avec une inhibition totale de croissance pour ce niveau de contamination. Ces résultats sont à mettre en relation avec les facteurs élevés de bioaccumulation calculés, qui sont de 57 ±6,3 µg Cd/g ps et de 734 ±70 µg Cd/g ps au bout de 14 jours pour l’exposition respectivement à 10 et 100 µg Cd/L. Des réponses génétiques révèlent l’impact du Cd sur le métabolisme mitochondrial et sur le photosystème d’Eolimna minima exposée à 10 et 100 µg/L avec des surexpressions de cox, 12S, d1 et psaA au bout de 7 jours d’exposition pour la concentration à 100 µg/L et de nad5, d1 et psaA au bout de 14 jours pour les 2 conditions. Notre étude est une première approche dans l’utilisation de la PCR-q sur diatomées benthiques d’eau douce. Les résultats obtenus laissent envisager des perspectives extrêmement intéressantes dans le cadre de développement de nouveaux outils de diagnostic de la qualité des eaux.
(pp. 1, 12/04/2026)
UR REBX, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Field translocation of diatom biofilms impacted by Cd and Zn to assess decontamination and community restructuring capacities
Metal wastes have been repeatedly shown to significantly disturb periphytic communities. This study considers an industrial contamination site subjected to remediation processes since 2007. With the aim of finding relevant bioindicators of the restoration capacity of such impacted hydrosystems, this study focussed on biofilm and diatom recovery kinetics. Biofilms were colonised at a reference site and in parallel at a metal-contaminated site. After 24 days, contaminated biofilms were translocated to the reference site to study the biofilm recovery potential for 9 weeks under natural conditions. Analyses from the community level – measures of metal bioaccumulation, cell densities and taxonomic investigations – to the individual level – measures of teratological forms – were performed. The results showed that Zn and Cd contents were rapidly depurated, reaching reference levels 3 and 9 weeks after translocation, respectively. A Principal Response Curve (PRC) analysis enabled to see the fast evolution of diatom communities, with species specific to the reference site growing in decontaminated biofilms from the 3rd week. After 9 weeks, we estimated that diatom community restructuring was complete, based on measurements of biovolumes and teratological form rates which both decreased to reference levels in decontaminated biofilms throughout the experiment. The different teratological types appeared to be good bioindicators of biofilm contamination and shed light on the duration of contamination. According to these results, different criteria can provide information on the recovery potential of periphyton. Biofilms proved to be good bioindicators of metal recovery and diatoms proved to be good bioindicators of community recovery.
(Ecological Indicators. vol. 18, n° 1470-160X, pp. 520-531, 12/04/2026)
UR REBX, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Adaptation aux variations des régimes hydrologiques (crues étiages) dans l’environnement fluvio estuarien de la Garonne Gironde : potentialités, mise à l’épreuve et gouvernance d’options d’adaptation
Caractérisation des impacts et vulnérabilités Garonne-Gironde face au changement climatique. Expérimentation d'options d'adaptation. Consilience, scénarios et conditions de diffusion d'options d'adaptation.
(pp. 10, 12/04/2026)
UR ADBX, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CNRS, GREThA, UB, CNRS, GEODE, UT2J, Comue de Toulouse, CNRS
Comparison of earthquake-triggered turbidites from the Saguenay (Eastern Canada) and Reloncavi (Chilean margin) Fjords: implications for paleoseismicity and sedimentology
High-resolution seismic profiles along with physical and sedimentological properties of sediment cores from the Saguenay (Eastern Canada) and Reloncavi (Chile) Fjords allowed the identification of several decimeter to meter-thick turbidites. In both fjords, the turbidites were associated with large magnitude historic and pre-historic earthquakes including the 1663 AD (M > 7) earthquake in the Saguenay Fjord, and the 1960 (M 9.5), 1837 (M ~ 8) and 1575 AD major Chilean subduction earthquakes in the Reloncavi Fjord. In addition, a sand layer with exoscopic characteristics typical of a tsunami deposit was observed immediately above the turbidite associated with the 1575 AD earthquake in the Reloncavi Fjord and supports both the chronology and the large magnitude of that historic earthquake. In the Saguenay Fjord, the earthquake-triggered turbidites are sometimes underlying a hyperpycnite associated with the rapid breaching and draining of a natural dam formed by earthquake-triggered landslides. Similar hyperpycnal floods were also recorded in historical and continental geological archives for the 1960 and 1575 AD Chilean subduction earthquakes, highlighting the risk of such flood events several weeks or months after main earthquake. In both fjords, as well as in other recently recognized earthquake-triggered turbidites, the decimeter-to meter-thick normally-graded turbidites are characterized by a homogeneous, but slightly fining upward tail. Finally, this paper also emphasizes the sensitivity of fjords to record historic and pre-historic seismicity.
(Sedimentary Geology. vol. 243-244, n° 0037-0738, pp. 89-107, 12/04/2026)
ISMER, UQAR, ISTO, INSU - CNRS, UO, UT, CNRS, M2C, UNICAEN, NU, INSU - CNRS, UNIROUEN, NU, CNRS, ISTO, INSU - CNRS, UO, UT, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LEHNA IPE, LEHNA, UCBL, ENTPE, CNRS, ULISBOA, GEOTOP, EPM, UdeM, UQAT, UQAR, UQAM, IPEV, M.E.N.E.S.R., LERN, ULaval
Cartographie des habitats intertidaux du bassin d’Arcachon par imagerie optique et radar
Objectifs : - Exploitation en synergie de données radar et optiques ; - Discrimination, identification et cartographie exhaustive des substrats durs et meubles ainsi que des principales espèces végétales micro à macroscopiques ; - Quantification optique/radar de paramètres biologiques (composition, abondance spécifique, répartition surfacique) et sédimentaires (minéralogie, teneur en eau) ; - Validation d’une ou plusieurs stratégies de cartographie valorisables par des services GMES (Programme INFOLITTORAL-1, programme Territoire de Démonstration), implicitement adaptées aux exigences des missions de gestion des domaines naturels et exploités.
(pp. 16 p., 12/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UMR TETIS, Cirad, IRSTEA